Vision correction is on the verge of a revolution. New technologies to measure the aberrations or distortions in the optics of the eye will soon be available to the public. These new wavefront measurement techniques such as Shack-Hartmann wavefront sensing or Talbot Interferometry can precisely measure the eye's aberrations so that vision may be corrected up to 20/10. Wavefront sensing is the method for rapidly, and very accurately, assessing the aberrations in an individual's eye to create a customized prescription for correction.
However, once the eye's aberrations have been measured, either by conventional methods or by wavefront sensing, these measurements must then be transferred into a vision correction system, such as eye surgery, spectacles, or contact lenses. Recent advances in laser refractive surgery techniques such as LASIK and photorefractive keratectomy, as well as improvements in spectacle lens manufacturing now enable the creation of highly accurate corrective prescriptions for individuals.
However, this is not the case with contact lenses. Popular soft contact lenses cannot achieve the same result as spectacles or laser refractive surgery because of dimensional variations in fabrication. Hard contact lenses, which may provide the platform to achieve the results of spectacles, are not as comfortable as soft contacts and lack the necessary positional stability on the eye.
Hybrid hard-soft contact lenses comprising a hard center portion and a relatively soft outer skirt have been developed to provide a platform for a corrective prescription and also provide the comfort of soft contact lenses. One drawback associate with such hybrid hard-soft contact lenses concerns a lack of a smooth transition between the soft and hard portions. Another drawback involves a lack of bonding strength between the soft and hard portions.
Accordingly, there exists a need for a hybrid contact lens having a junction that provides a smooth transition between the soft and hard portions as well as sufficient bonding strength between the soft and hard portions for an improved surface. There also exists a need for methods of manufacturing such a lens.
Contact lenses that exhibit high oxygen permeability are generally preferred for the health and comfort of the eye. However, high and hyper DK materials (e.g., materials having a DK value of at least 30) that exhibit the requisite oxygen permeability are notoriously difficult materials to bond with the soft peripheral materials found in most hybrid contact lenses. Further, the rigid center material is highly sensitive such that the penetration of soft peripheral materials and other chemical solutions into the hard center portion will alter the physical characteristics of the sensitive high DK center portion.
Accordingly, there exists a need for a hybrid contact lens having a high or hyper DK center portion that includes a smooth transition between the soft and hard portions as well as sufficient bonding strength between the soft and hard portions for an improved surface. There also exists a need for methods of manufacturing such a lens.
Astigmatism is a defect of the eye in which rays of light entering the eye fail to meet in a correct focal point after passing through the optical system, thereby resulting in a blurred and imperfect image. The defect is usually the result of a mis-shaped or toric cornea, and the correction of astigmatism may be accomplished through the use of a tone contact lens. Hybrid hard/soft contact lenses are also difficult to manufacture since the hard and soft materials are not easily bonded to produce a lens with acceptable boundaries. Further, the known techniques for making hybrid lenses are not adaptable to the manufacture of a molded lens.
Accordingly, there exists a need for a toric hybrid contact lens having a junction that provides a smooth transition between the soft and hard portions as well as sufficient bonding strength between the soft and hard portions for an improved surface. There also exists a need for methods of manufacturing such a lens.